18. Pollution of Air and Water Science class 8 in English Medium ncert book solutions Chapter Review

Chapter Review:

• The contamination of air by impurities like smoke and poisonous gases which may have a harmful impact on the living and the non-living components, this is called air pollution. 
• The substances which contaminate the air and water. These are called pollutants.

• Components of air is Nitrogen 78%, Oxygen 21%, carbon dioxide, argon, and methane.

•  Ozone layer prevents us to the ultraviolet rays coming from the sun. 

• Ultraviolet rays carry radiations Which harm our body and cause various diseases like cancer and skin disorders. 

• The sulpher dioxide and nitrogen dioxide form sulphuric acid and nitric acid react with moisture and water vapour in atmosphere. These form rain acidic . This is called acid rain. 

• There is raising the quantity of CO₂ in atmosphere resulting in increasing continue average temperature of atmosphere. This is called global warming. 

• If the sunlight enters into nursery (glass house) which is not allowed to come out. The trapped heat warms the green plants. Similarly our atmosphere trapped radiation and warms the earth. This effect is known as green house effect. 

• The full form of CFCs is Chlorofluorocarbons. 

• The full form of WWF is Word wide Fund. 

• The green house gases are CO₂ , Methane and nitrous oxide etc. 

• An ambitious plan to save the river, called the Ganga Action Plan was
  launched in 1985.

• Water which is suitable for drinking is called potable water.

• The 4R principle is  Reduce, reuse, recycle and recover.